I had an idea about this. what if one were to forge weld four "L" bent strips of steel onto the steel centre, like so:
'>
(made by swordandsheild)
so that the flats were parallel to the centre, and then spit these strips somehow, so that you had eight flanges.
then perhaps hand sharpen them?
i know in this picture it is simply MIG welded, but i think this could be forge welded, with a bit of careful thinking.
anyway, you get my point.
do that, then "somehow" split the four flanges to get eight, sharpen them, yada yada.